JPH0358077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for inspecting the occurrence of coating failure on fuel pins of a nuclear reactor cooled by liquid metal. Such devices are commonly referred to as "damaged fuel detection devices."

A common approach to this subject is to install coolant sampling pipes (one for each fuel assembly).
It was to use it. A coolant sampling pipe extends to a respective port of a selection valve, the valve having a rotating selection arm with a friction seal;
Sampling pipes are selected to sequentially measure the coolant appearing at the ports of the valve. British patent specification 1287536 is an example of this approach. A first pump draws coolant along the sampling pipe and a second pump draws coolant along the selection arm to the delayed neutron counter.

However, the friction seal is the weak point. If it breaks, it causes damage to the sampling system that is difficult to replace.

It is an object of the present invention to provide a sampling device that does not require seals that rub during use, as such seals would be damaged. In accordance with the present invention, a damaged fuel detection system sequentially inspects liquid metal coolant sampling pipes to detect products indicative of fuel damage within the liquid metal coolant. A pump for pumping the coolant to the outlet points of the pipe and a rotating collector that traverses or scans these outlet points sequentially, and the coolant can be traversed between the rotating collector and the outlet points. This objective is achieved by arranging the exit point of the pipe and the rotating collector so that it can be scanned with a gap.

The present invention will be described in detail below with reference to the accompanying drawings.

The multiple (typically 70) sodium sampling pipes 10 shown are multi-duct HALIP
(Helical annular linear induction pump) The liquid passes through the annular chamber of 11 and extends vertically from there to the open end 10b, and discharges liquid into the liquid reservoir 12 from the downward outlet port 10a provided below the open end 10b. I'm starting to do that. Open end 10b serves to maintain a constant head at outlet port 10a. Immersed in the reservoir 12 is a rotating sampling unit 13, which comprises a vertical rotary tube 14 with a closed end, a selection pipe 15 disposed inside this tube 14, and a rotating sampling unit 13 with a closed end. and another pump 16 immersed in a bath formed by a closed end. pump 16
The liquid is discharged through a duct 17 provided with a flow meter 18 on the outside. The duct 17 is connected to a sample measuring pot 19 which has an overflow 20 adapted to discharge liquid into the reservoir 12. The mouth of the selection pipe 15 moves over the outlet port 10a of the pipe 10 while maintaining the gap 15a. The liquid level of sodium is 2
It is shown as 1. Liquid source 1 below the sodium liquid level 21
An outlet 22 from 2 is provided. The sodium from this outlet 22 can be monitored for products indicative of fuel failure.

A pump 11, which is wetted with sodium inside and outside the pipes 10, causes a sample of sodium to flow through all the pipes 10 and
0 from end 10b and outlet port 10a (excluding the pipe being sampled) to sump 12;
Next, the liquid is discharged from the outlet 22. The sodium in the sump 12 is monitored for products indicative of a fuel pin failure; Monitored for product indicating pin position. The tubes 14 may be rotated continuously in steps or smoothly (e.g. 3 rotations per hour), or if special monitoring of one particular pipe 10 is deemed necessary, it may be rotated to monitor that pipe. It may be left stationary.

[Brief explanation of drawings]

The accompanying drawings schematically show, in cross-section, a pump and mechanical sampling valve arrangement according to the invention. 10... Sampling pipe, 10a... Outlet port, 11... HALIP (helical annular linear induction pump), 12... Liquid reservoir, 13... Rotating sampling unit, 14... Rotating tube, 15... Selection pipe, 15
a... Gap, 16... HALIP, 17... Duct, 18
...flow meter, 19...sample measurement pot, 20...overflow, 21...liquid level, 22...outlet.

Claims (1)

[Claims] 1. In a broken nuclear fuel pin detection device for a fast reactor cooled by liquid metal coolant, a first pump 11 supplies liquid metal coolant through a plurality of sampling pipes 10 extending upward from the first pump 11. The sampling pipes 10 have an open upper end 10b and an outlet port 10a below the upper end, and a sump 12 receives liquid metal coolant discharging from the outlet port 10a of the sampling pipes 10. , has a lower discharge outlet 22 for discharging the liquid metal coolant therein, the lower end of the upright collection tube 14 rotating within the sump 12 is closed, and the collection tube 14 has a lower discharge outlet 22 for discharging the liquid metal coolant therein; a second pump 16 for the material, a selection pipe 15 extending from the collection tube 14 close to said outlet port 10a;
Collecting liquid metal coolant from the second pump 1, rotation of the collection tube 14 causes the selection pipe 15 to face each outlet port 10a sequentially with a gap therebetween.
The duct 17 extending upward in which 6 is arranged is the collection pipe 1
Sampling the liquid metal coolant in 4 into pot 19
The sampling pot 19 has an overflow 20 for returning the liquid metal coolant therein to the sump 12, and the flow meter 18 is connected to the duct 17.
The flow rate of liquid metal coolant in the sampling pot 1 can be detected and thereby monitored at said discharge outlet 22 for products indicative of fuel pin failure;
9 to monitor the liquid metal coolant in outlet port 1.
A broken nuclear fuel pin detection device characterized by detecting a product indicating the position of a broken pin from the position of a selection pipe 15 with respect to 0a.